Wet meadows of the alliance <Emphasis Type="Italic">Molinion</Emphasis> and their environmental gradients in Slovenia

The main objective of this study was to examine the relationships between wet meadow plant communities of Molinon alliance and their environmental conditions in Slovenia. The ecology of these communities was analysed in detail. The study provides the data on the vegetation and environmental parameters, the significance of parameters for the plant species composition, most important environmental gradients and differences between plant communities. In all plots the vegetation was recorded and soil parameters were analysed (pH, plant-available P and K, N^t, organic C, C/N ratio, exchangeable Ca²⁺, Mg²⁺, K⁺, Na⁺, H⁺, electrical conductivity, base saturation). Other conditions were also considered (e.g., mean annual temperature and precipitation, humidity index, mean Ellenberg moisture and nutrient value) to test possible correlations as well. Vegetation was classified by means of multivariate cluster analysis, while vegetation-site relationships were examined with direct gradient analysis (CCA). Six associations from the Molinon alliance (Selino-Molinietum, Plantagini altissimae-Molinietum, Carici davallianae-Molinietum, Gentiano-Molinietum litoralis, Junco conglomerati-Betonicetum and Sanguisorbo-Festucetum commutatae) were identified and analysed. Soil reaction was identified as most significant environmental parameter explaining the variation of the studied vegetation. There are several statistically significant differences in site conditions between the communities (pH, moisture, nutrient status, Ca²⁺). The studied associations represent clearly defined ecological units.     

Major plant communities of the Carson Desert (Nevada), North America's coldest and driest desert

This paper describes the vegetation of the Carson Desert (Nevada, USA) based on a phytosociological analysis of its major plant associations, as determined by the Braun-Blanquet method. Diagnostic tables, climatic, edaphic, and biogeographical data were used to establish floristic affinities among identified plant communities and to interpret their distributions in zonal gradients. Their syntaxonomic positions in the classes Allenrolfeetea occidentalis and Artemisio tridentatae–Juniperetea osteospermae, and in the new class Sarcobatetea vermiculati were also established. Three associations (Atriplici confertifoliae–Sarcobatetum baileyi, Atriplici canescentis–Psorothamnetum polydenii, and Suaedo moquinii–Sarcobatetum vermiculati) are described here for the first time along with the order Sarcobatetalia vermiculati and the alliance Sarcobation vermiculati.     

Plant communities structure and composition in three coastal wetlands in southern Apulia (Italy)

In this paper the results of a study on the composition and the distribution of the plant communities in three coastal areas of southern Apulia are presented. A total of about 180 vegetation relevés were performed following the Braun-Blanquet phytosociological method. Vegetation data were analysed using both classification (UPGMA, similarity ratio) and ordination methods (including Non-metric Multidimensional Scaling (NMS) and Detrended Correspondence Analysis (DCA). The relevés are distributed in the following classes: Molinio-Arrhenateretea, Phragmito-Magnocaricetea, Juncetea maritimi, Sarcocornietea fruticosae, Saginetea maritimae, Thero-Salicornietea, Helianthemetea guttati. Detailed information about structure and zoning of the detected plant communities are here provided. Two new associations, belonging to the Alkanno-Maresion nanae alliance (microphytic ephemeral plant communities growing on sandy soils, Helianthemetea guttati class) have been described here, both in the “Torre Guaceto” site. The area of “Le Cesine” showed the highest total number of plant communities, while the “Saline di Punta della Contessa” site revealed the largest number of Sarcocornietea fruticosae plant communities.     

Cave lithology determining the structure of the invertebrate communities in the Brazilian Atlantic Rain Forest

In Brazil, only limestone caves and a few caves in sandstone, iron ore and granite rocks had their invertebrate communities evaluated. Being such, the present study aimed to promote a comparative analysis of the structure of the invertebrate communities in caves associated to carbonatic, magmatic, siliciclastic and ferruginous rocks of the Brazilian Atlantic forest. Significant differences in the relative richness, abundance and diversity were observed between lithologies. The average relative richness was higher in the ferruginous caves (0.53 spp). The total number of troglomorphic species was significantly different among caves and the highest average richness occurred at ferruginous caves (5.79 spp/cave). Siliciclastic, carbonatic and magmatic caves presented a higher quantitative similarity of the fauna. Ferruginous caves revealed communities with a fauna composition different from the other lithologies. The total richness of invertebrates correlated significantly and positively with the linear development in the siliciclastic caves (R_s = 0.67, P < 0.05), carbonatic (R_s = 0.71, P < 0.05) and ferruginous (R_s = 0.74, P < 0.05). The rock type in which the cave is inserted can determine differences in the richness of invertebrate troglophyles and troglobites. Therefore, on creating value attributes, the size of the caves should always come related to their lithology by the fact that same sized caves associated to different lithologies, possess communities with quite diverse structures.     

Vegetation of rock crevices of the montane and colline zones in the Pamir-Alai and Tian Shan Mts in Tajikistan (Middle Asia)

The paper presents the results of phytosociological research conducted on the vegetation of rock habitats in the montane and colline zones of the Pamir-Alai Mountains (Tajikistan). During field surveys done in 2010–2013, 122 phytosociological relevés were sampled. Plant species were recorded according to the Braun-Blanquet cover-abundance scale. The vegetation studies were carried out generally in the western Pamir-Alai and south-western Tian Shan Mts, especially in the Zeravshan, Hissar, Hazratishoh, Darvaz, Rushan, Turkestan, Kuramin and Vanch ranges. A synopsis of the rock communities of the montane and colline zones in Tajikistan is proposed. The collected material presents most of the variability among the plant communities of rock crevices and fissures on calcareous as well as acidic substrates in the montane and colline zones in Tajikistan. As a result of field research and numerical analyses, eight associations have been distinguished: Scutellarietum hissaricae, Scutellarietumschugnanicae, Scutellarietum zaprjagaevii, Scutellarietum baldshuanicae, Tylospermetumlignosae, Dionysietum involucratae A. Nowak, M. Nobis, S. Nowak & A. Nobis, 2014, Nanorrhinetum ramosissimi, Campanuletum albertii and the community of Scutellaria adenostegia within new alliance – Caricion koshevnikovii. The main factors determining the species composition of classified associations seem to be the geography of the distribution range, elevation above sea level, rock type and exposition.     

Identification of roots in lava tube caves using molecular techniques: implications for conservation of cave arthropod faunas

Lava tube cave ecosystems on the volcanic islands of Hawai‘i support communities of rare and highly specialized cave arthropods. In these cave ecosystems, plant roots, both living and dead, provide the main energy source for cave animals. Loss of deep-rooted plants over caves will affect populations of cave-adapted animals living below. Furthermore, the loss of native plant species will likely eliminate host specific cave animals. Thus, identification of plant roots currently found in caves is necessary for the development of effective management actions that encourage the growth of appropriate deep-rooted plant species, thereby protecting the underlying cave ecosystem. We used molecular techniques to identify plant roots found within cave ecosystems on the islands of Maui and Hawai‘i. Sequences of the internal transcribed spacer (ITS) regions and the 5.8S gene of nuclear ribosomal DNA from cave roots were compared to sequences of known plant species either collected on the surface over the footprint of each cave or to sequences accessioned in GenBank. Roots in the cave ecosystem studied on Maui belonged to two alien tree species: Eucalyptus tereticornis and Grevillea robusta. Within the Hawai‘i cave ecosystem, roots of two plant species were identified: the alien tree G. robusta and the native vine Cocculus orbiculatus. The Maui cave ecosystem supports populations of at least 28 species of arthropods, including eight that are blind obligate cave inhabitants. The Hawai‘i cave ecosystem supports 18 arthropod species, of which three are cave-adapted. Creating protected reserves around biologically significant caves, controlling, and preventing the introduction of harmful invasive plant species within the cave footprint, and encouraging the establishment of deep-rooted native plant species is essential for the continued survival of the unique ecosystems found within Hawaiian lava tube cave systems.     

Distribution patterns and changes of aquatic plant communities in Napahai Wetland in northwestern Yunnan Plateau, China

Using GPS technology and community research methods for plant communities, we investigated the distribution patterns of aquatic plant communities in the high plateaus of the Napahai Wetlands, Yunnan, China, as well as the species changes of plant communities compared with that of 24 years ago since 2005. We found that the types and numbers of aquatic plant communities have changed. Some pollution-tolerant, nutrient-loving plant communities such as Scirpus tabernaemontani, Zizania caduciflora, Myriophyllum spicatum, and Azolla imbricata flourished, while the primary aquatic plant communities were reduced or even disappeared. The number of aquatic plant communities were increased from nine to 12 with the addition of two new emergent plant communities and one new floating-leaved plant community. The increase in emergent plant communities was significant. From east to west and from south to north, various types of plant communities were continuously distributed, including floating-leaved plant communities, emergent plant communities and submerged plant communities. The composition of the communities became more complicated and the number of accompanying species increased, while the percentage ratio of dominant plant species declined. In 2005, the coverage of emergent plant communities was the largest (528.42 hm²) followed by submerged plant communities (362.50 hm²) and the floating-leaf plant communities was the smallest (70.23 hm²). The variations in the distribution of aquatic plant communities in the Napahai Wetlands reflect the natural responses to the change of the wetland ecological environment. This study indicates that human disturbances have led to an inward movement of the wetland shoreline, a decrease in water quality and a reduction in wetland habitat. __________ Translated from Acta Ecologica Sinica, 2006, 26(11): 3624–3630 [译自: 生态学报]     

Characterizing the spatial structures of riparian plant communities in the lower reaches of the Heihe River in China using geostatistical techniques

Geostatistical techniques are used to evaluate spatial characteristics of riparian plant communities that were mapped within a portion of the lower reaches of the Heihe River. The spatial structures of different plant communities were characterized using nugget, range and sill parameters of spherical or exponential model variograms. Model variograms revealed different plant communities with distinctive spatial properties that were quantified effectively by the parameters used in these models. Model variograms were fit to experimental variograms calculated from diameter at breast height and plant cover data collected for three 2,000 m × 5 m, nine 500 m × 5 m, and three 200 m × 2 m transects. The 2,000 m × 5 m transects were oriented perpendicular to the river and the other transects were located in such a way as to sample communities dominated by different plants. Riparian plant communities in the lower reaches of the Heihe River show patterns of patchiness, and the plant communities are mainly dominated by mature Populus euphratica, young P. euphratica, Tamarix chinensis, and Sophora alopecuroides. The maximum model variogram range for all communities was 55 m, suggesting that transects must be at least this long in order to be able to classify them unambiguously into recognizable communities. Experimental variograms were calculated for all plants in each of four mapped plant communities. The results show that the T. chinensis and S. alopecuroides dominated plant communities have distinctively large ranges, and the spatial structures of P. euphratica dominated plant communities show multiscale change. In the 2,000 m × 5 m transects, the spatial structures of riparian plant communities show a distinct change at the scale of 430 m, because this scale also is the scale of vegetation patchiness turnover, and at scales of more than 430 m the spatial structure of the community increases significantly. These findings confirm the potential of using high-resolution remote sensing data and geostatistics for determining the vegetation community structures of riparian plant communities.     

Temporal changes in species composition in Fescue Prairie: relationships with burning history,time of burning,and environmental conditions

Historically, fires occurred throughout the year in the Fescue Prairie of Canada, but little is known about plant community responses to burning at different times of the year. Composition of plant communities was determined annually for 6 years after burning one or three times in a remnant Fescue Prairie in central Saskatchewan. A multiple-response permutation procedure indicated that plant community composition was different in the two burning histories (P < 0.001) and among times of burning (P < 0.001). Variables related to plant community composition after burning were evaluated using Non-metric Multidimensional Scaling. Three gradients explained 86% of the variation in composition of plant communities. Environmental conditions leading up to burning and at the time of burning correlated poorly with species composition. Differences in composition of plant communities were attributed primarily to burning history, cumulative precipitation in the 12 months before sampling, cumulative cold-stress days in the 12 months before sampling, cold-stress days in March and April, and months since burning. Plant communities burned once responded negatively to increasing cold-stress days while those burned three times responded positively to cold-stress days. Cover of Festuca hallii and Symphoricarpos occidentalis was 88 and 350% greater after one burn as compared to three burns, whereas cover of Carex obtusata, Carex pensylvanica, and Elymus lanceolatus was 126, 53, and 220% greater after three burns than after one burn. Festuca hallii, Galium boreale, Pulsatilla patens ssp. multifida, Symphoricarpos occidentalis, and Symphyotrichum ericoides had the highest indicator value of a single burn; Carex obtusata, Elymus lanceolatus, and Koeleria macrantha had the greatest indicator values for sites burned three times. Longer-term effects of burning history exert a strong influence on plant community composition while short-term conditions after burning, namely, precipitation and cold-stress days, appear important in controlling species responses and composition of plant communities in Fescue Prairie.     

Weak habitat specificity in ectomycorrhizal communities associated with Salix herbacea and Salix polaris in alpine tundra

This study explores mid-alpine ectomycorrhizal communities on Salix herbacea and Salix polaris in plant communities differing in nutrient status and snow conditions. Plant species were identified by tracking roots back to above ground structures while fungal species were identified using molecular methods. The fungi were identified to 34 molecular operational taxonomic units (MOTUs)/species but species accumulation curves indicated that the communities were only partially sampled. The estimated total species richness was 49 (±9 SD) MOTUs/species. No significant ectomycorrhizal community specificity was found between the two plant species and only weak specificity between different plant communities. Furthermore, no difference in proportion of colonized root tips could be demonstrated between plant communities. However, some fungal taxa showed tendencies to associate with specific environmental conditions. Sebacinaceae, Inocybe egenula, Russula cf. emetica, and a Tomentella sp. were found in meadow communities but not in the heath communities. Sistotrema cf. alboluteum and Tomentella cf. terrestris were only found in the dry and mesic heath communities. Classifications into exploration types showed that the contact type is more abundant in the dry heath community than the other communities. Cenococcum geophilum was the most common species but Cortinarius spp., Russula spp., Tomentella spp., and Lactarius spp. were also common. This study confirms that alpine communities are rich in ectomycorrhizal fungi including species from a wide variety of fungal lineages and also show that many dominant species have wide ecological amplitude.     

The vegetation of alpine belt karst-tectonic basins in the central Apennines (Italy)

Abstract

The vegetation communities of the karst-tectonic basins of the Majella massif alpine belt were studied using the phytosociological methods, and analysed from coenological, synchorological and syntaxonomical viewpoints. During the field-work, 115 relevés were performed using the phytosociological approach of Braun-Blanquet, and these relevés were further subjected to multivariate analyses. Eight clusters of relevés resulted from the numerical classification. The plant communities identified in the study area were ascribed to the following five associations, two sub-associations and one community type: Leontopodio – Seslerietum juncifoliae (ass. nova); Helianthemo – Festucetum italicae (ass. nova); Gnaphalio – Plantaginetum atratae; Taraxaco – Trifolietum thalii gnaphalietosum magellensis (subass. nova); Luzulo italicae – Nardetum, Carici – Salicetum retusae; Saxifrago – Papaveretum julici, Saxifrago – Papaveretum androsacetosum (subass. nova), Plantago atrata and Leontodon montanus community. The distribution of these communities within the karst basins was found to be related to variations in topographic and geomorphological parameters, such as altitude, slope, soil availability and stoniness. All the new associations proposed in this paper belong to the suballiance Leontopodio – Elynenion and to the alliance Seslerion apenninae, both of which are endemic to the central Apennines. In order to compare the plant community types identified within the Majella massif to similar associations found in the rest of the Apennine chain, synoptic tables were constructed. Finally, a comparative phytogeographical analysis of the alpine belt vegetation of the Apennines, Dinarides, southern Balkans and eastern Alps is presented.     

The Chrysopogono grylli-Nerietum oleandri association in Croatia as compared with other Rubo ulmifolii-Nerion oleandri communities (Tamaricetalia,Nerio-Tamaricetea) in the Mediterranean

Abstract

A new association, Chrysopogono grylli-Nerietum oleandri, situated in the south of Croatia, is proposed. According to its floristic structure, physiognomy and ecology, it belongs to the Rubo ulmifolii-Nerion oleandri alliance (Tamaricetalia, Nerio-Tamaricetea). It is the only association with Nerium oleander in Croatia. This community has developed along a temporary watercourse as a vegetation exclave (extrazonal stand) within the climazonal evergreen forest vegetation of the Oleo-Ceratonion alliance. The association has a thermophilous character and a large number of companions from the Quercetalia ilicis and Scorzonero-Chrysopogonetalia communities. This report compares the floristic composition of this association with others of the Rubo ulmifolii-Nerion oleandri alliance from other Mediterranean areas. The Croatian association is most similar to the Spartio-Nerietum oleandri association from the Ionian side of Calabria (south Italy). The syntaxonomic status of the Montenegrin association Andropogono distachyi-Nerietum oleandri was determined, and the status of the stands with Nerium oleander is discussed.     

Biodiversity in different successional stages of Mediterranean enclaves distributed along Sinop Peninsula (Turkey)

The aim of this research was to evaluate plant diversity and the relationships between the distribution of Raunkiaer life forms and community structure, and species richness, at different successional stages in communities of Quercus ilex L., Erica arborea L. and Sarcopoterium spinosum (L.) Spach., distributed as enclaves in Sinop Province. Permanent sample plots were selected to determine plant diversity. The cover percentage of each plant species was recorded monthly during two vegetation periods. Raunkiaer life forms, and the Shannon–Wiener, Evenness, Simpson and Margalef indexes were determined. Twenty-three species in Quercus ilex, 96 species in Erica arborea, and 148 species in Sarcopoterium spinosum were identified. Hemicryptophyte dominancy was observed followed by phanerophytes in the Q. ilex community, and therophyte and hemicryptophyte dominancy in the E. arborea and S. spinosum communities, respectively. It was determined that the S. spinosum community was the most heterogeneous community while the Q. ilex community was more uniform than other communities. The variation in diversity indexes, homogeneity, and composition of life forms among communities adopting a similar climatic environment could result from a differentiation of environmental factors, which impact on community structuring, from biotic to abiotic at different successional stages of Mediterranean communities.     

艾比湖湿地植物群落土壤酶活性特征及影响因素

为研究艾比湖湿地不同植物群落土壤酶活性的季节变化规律及影响因素,2015—2016年5、8和11月以绕湖一周范围内的梭梭-柽柳、梭梭、胡杨、芦苇为研究对象,对4种植物群落下不同月土壤过氧化氢酶、磷酸酶和脲酶活性及理化因子进行分析。结果表明:(1)各植物群生境的差异使酶活性有明显变化,呈现出芦苇群落梭梭群落胡杨群落梭梭-柽柳群落。不同植物群落下酶活性具有明显的季节变化,梭梭-柽柳、梭梭、胡杨群落土壤过氧化氢酶、磷酸酶、脲酶的峰值分别出现在5月(2.72、3.31和2.94 mg/g)、(1.18、1.32和0.69 mg/g)和(0.18、0.34和0.17 mg/g),而芦苇群落3种酶活性的峰值出现在8月(5.18、1.20和0.66 mg/g);谷值均出现在11月。(2) 4种植物群落下各月土壤酶活性与土壤有机质、全磷呈显著正相关,而与土壤盐分呈负相关;除芦苇群落外,其他群落8月土壤温度与酶活性呈负相关。(3) 4种植物群落各月间土壤酶活性受多因素的共同影响,土壤盐分、有机质、全磷是影响艾比湖湿地不同植物间土壤酶活性的主导因素,土壤温度和含水量对不同月土壤酶活性的影响更为显著。     

Transgenic tobacco revealing altered bacterial diversity in the rhizosphere during early plant development

The rhizosphere constitutes a complex niche that may be exploited by a wide variety of bacteria. Bacterium–plant interactions in this niche can be influenced by factors such as the expression of heterologous genes in the plant. The objective of this work was to describe the bacterial communities associated with the rhizosphere and rhizoplane regions of tobacco plants, and to compare communities from transgenic tobacco lines (CAB1, CAB2 and TRP) with those found in wild-type (WT) plants. Samples were collected at two stages of plant development, the vegetative and flowering stages (1 and 3 months after germination). The diversity of the culturable microbial community was assessed by isolation and further characterization of isolates by amplified ribosomal RNA gene restriction analysis (ARDRA) and 16S rRNA sequencing. These analyses revealed the presence of fairly common rhizosphere organisms with the main groups Alphaproteobacteria, Betaproteobacteria, Actinobacteria and Bacilli. Analysis of the total bacterial communities using PCR-DGGE (denaturing gradient gel electrophoresis) revealed that shifts in bacterial communities occurred during early plant development, but the reestablishment of original community structure was observed over time. The effects were smaller in rhizosphere than in rhizoplane samples, where selection of specific bacterial groups by the different plant lines was demonstrated. Clustering patterns and principal components analysis (PCA) were used to distinguish the plant lines according to the fingerprint of their associated bacterial communities. Bands differentially detected in plant lines were found to be affiliated with the genera Pantoea, Bacillus and Burkholderia in WT, CAB and TRP plants, respectively. The data revealed that, although rhizosphere/rhizoplane microbial communities can be affected by the cultivation of transgenic plants, soil resilience may be able to restore the original bacterial diversity after one cycle of plant cultivation.     

Vegetation succession at the abandoned Ogushi sulfur mine, central Japan

We surveyed plant community development at the abandoned Ogushi sulfur mine. We found seven communities dominated by the following respective species: Deschampsia flexuosa, Miscanthus sinensis, shrub willow, Gaultheria miqueliana–Betula ermanii, Sasa senanensis–Betula ermanii, willow–Betula ermanii, and Sasa kurilensis–Abies veitchii. We examined the succession of these communities, in which younger communities of low height and ground cover contained seedlings of the successive communities that were taller and had higher ground cover. To understand the development of these different communities, we surveyed damage from mining pollution and effects of immature soils formed by landslides. The average pH (H₂O) was 4.12, and aluminum concentrations were not sufficiently high to damage plant growth, except in areas where sulfur had been mined. The organic carbon and nitrogen content in soil samples were very low because of a delay in soil development caused by a large landslide in 1937. Hence, succession was positively correlated with the soil development stage. The delay in soil development after a large landslide influenced the seven successional steps of the plant communities, but mineral poisons at the abandoned Ogushi sulfur mine had no effect on succession.     

Effects of organic matter availability on the life history and production of a top vertebrate predator (Plethodontidae: Gyrinophilus palleucus) in two cave streams

1. Surface ecosystems provide the primary source of organic matter to many cave communities. Variation in the strength of connectivity to the surface suggests that some caves may be more resource‐limited than others. To test this, we examined diet, prey availability and production of an obligate cave salamander Gyrinophilus palleucus (Plethodontidae), a top predator, in two south‐eastern U.S.A. caves with different levels of organic matter (Tony Sinks cave, 165 g AFDM m^?2; Bluff River cave, 62 g AFDM m^?2). 2. We quantified density, biomass, growth rate, production and diet of G. palleucus monthly for 21 months. Diet composition, differences in prey communities and seasonal patterns in prey consumption were also analysed. 3. Salamander density, biomass and secondary production were significantly greater in the high organic matter cave (0.10 m^?2, 0.18 g AFDM m^?2, 0.12 g AFDM m^?2 year^?1) than in the low organic matter cave (0.03 m^?2, 0.03 g AFDM m^?2, 0.01 g AFDM m^?2 year^?1). Although growth rates were not statistically different between the two cave salamander populations, low recaptures probably influenced this result. 4. Isopoda prey were the major contributor to salamander production in the high organic matter cave (69%). In the low organic matter cave, production was provided by isopods (41%) and oligochaetes (20%). The lower number of prey taxa contributing to salamander production in the high organic matter cave suggests the ability to forage more selectively. 5. The differences in foraging strategy, density, biomass and secondary production were probably related to differences in the strength of surface connectivity, which controls organic matter supply. Links between basal resource level and top predator performance show the importance of bottom‐up limitation in the food webs of caves and other detritus‐based ecosystems.     

盐城滨海滩涂湿地典型植物群落土壤微生物组成与结构特征

土壤微生物是生态系统维持正常结构与功能的重要组成部分,为探究盐城滩涂典型湿地土壤微生物群落结构特征,以江苏盐城滩涂互花米草、藨草、盐地碱蓬、芦苇及淤泥质光滩5种典型群落为对象,采用16S rRNA高通量测序技术分析0—10 cm(表层)、10—30 cm(中层)、30—60 cm(深层)土壤微生物多样性及群落结构。结果表明：(1)几种植物群落间,土壤微生物群落结构差异较大,主要体现在细菌群落结构的差异性,古菌群落结构差异相对较小。光滩与植物群落间,在土壤细菌种类及相对丰度上差异相对较大,互花米草群落与本土植物群落间,在微生物群落的细菌种类组成上存在较大差异;藨草群落土壤表层微生物群落结构与互花米草群落相似,深层与盐地碱蓬、芦苇群落相似。(2)同一群落不同层次土壤微生物群落结构相似,差异小于不同群落间土壤微生物群落的结构差异性;不同群落对应层次间,表深层土壤中五种群落土壤微生物多样性存在显著差异,中层土壤中五种群落微生物多样性差异不显著。总体上,植物群落类型对土壤微生物群落结构的影响大于土壤深度;与本土植物群落相比,互花米草群落土壤主要优势门微生物种类差异较小,但部分优势门微生物相对丰度...     

Bacterial composition in brassica-cultivated soils with low and high severity of clubroot

The natural bacterial communities of the soil–plant system are relevant in the process of suppressing diseases caused by soilborne plant pathogens. However, little is known regarding the structure of these communities in soils cultivated with brassica vegetables and their relationship with clubroot severity, a disease caused by Plasmodiophora brassicae. In the present study, the composition of bacterial communities in soils cultivated with cauliflower with distinct levels of disease severity was compared. The bacterial composition in soils with lower and higher clubroot severity differs in phylum and genera levels. Soils associated with plants with lower disease severity showed predominance of Kaistobacter, Flavisolibacter, Sphingobacterium, Koribacter, Nitrospira, Bradyrhizobium and Bacillus. Our study reinforces the importance of management strategies that promote improving the physical–chemical characteristics of soil, which are essential to modulate bacterial populations correlated with plant disease suppression.     

Halocnemum M. Bieb. vegetation in the Mediterranean Basin

The aim of the article is the syntaxonomic interpretation of hyperhalophilous woody or semi-woody vegetation with Halocnemum M. Bieb. along the coasts of the Mediterranean Basin. For this area, the two species of Halocnemum, H. strobilaceum (Pall.) M. Bieb. and H. cruciatum (Forssk.) Tod. are identified; their morphological characteristics, synonymy and distribution are here described. The study carried out of particular aspects of the plant morphology and the micromorphological characteristics of the seeds collected from different places in the Mediterranean allows to better differentiate the two species. Vegetation studies already done in many communities of the Mediterranean by several authors threw into great confusion because only H. strobilacem has been recognized as a dominant species. As regards the syntaxonomic analyses of the vegetation, the authors refer to the proposals already made by various scientists for the vegetation of inland salt basins of Eurasia and the Irano-Anatolian area, who suggested the classes Kalidietea foliate and Halocnemetea strobilaceiirano-anatolica, respectively. Conversely, in the Mediterranean Basin, the vegetation study is present only in coastal areas where it is considerably impoverished in the number of species. Therefore, the authors propose to include hyperhalophilous, woody and fruticose vegetation in the class Sarcocornietea fruticosae. However, the phytosociological and ecological diversity is highlighted proposing the order Halocnemetalia cruciati in which both the alliance Halocnemion strobilacei, for middle Eastern Europe, and the alliance Halocnemion cruciati, for North Africa with penetrations in the Western and Eastern Europe up to the Middle East coast, are included. This new interpretation has required the correction of the names of two associations (Frankenio corymbosae–Halocnemetum cruciati and Zygophylloalbi–Halocnemetumcruciati) and the proposal of two new associations Arthrocnemo machrostachyi–Halocnemetum cruciati and Halocnemo cruciati–Sarcocornietum fruticosae. A further proposal concerns the addition of the alliance Limoniastrion monopetali, previously included in the order Limonietalia, in the order Halocnemetalia cruciati.